High-frequency heating apparatus

ABSTRACT

A high-frequency heating apparatus, in which the high-frequency energy is uniformly distributed in a heating chamber for effectively heating the matter in the heating chamber. An energy distribution modifying means is provided in conformity to the shape of the heating chamber and on at least one of coaxial inner and outer conductors defining a cylindrical passage, which communicates with a waveguide coupled to a high-frequency oscillator. The high-frequency energy from the high-frequency oscillator is guided through the waveguide and the cylindrical passage to enter the heating chamber and is uniformly distributed in the heating chamber through the energy distribution modifying means.

United States Patent 4 Suzuki et al.

' APPARATUS [72] Inventors: Ryull Suzuki, Nara; Selkl Yohnekl, Ya-

matokoriyama-shi, both of Japan [73] Assignee: Mllfllfllllll Electricllldlll'lfl C0,, Ltd

Osaka, Japan [22] Filed: Nov. 27, 1970 [21] Appl. No.: 92,984

[30] Foreign Application Priority Data Dec. 1, 1969 Japan..." ..44/96984[52] US." 9/10-55 [51] Int. Cl. "0510 9/06- [58] neldolsearchn'w,..219/10.5 5

[56] RefermcesClted UNITED STATES PATENTS 3,436,507 4/1969 Puschner"219/1055 3,532,847 10/1970 Puschner ..2l9/10.55 3,364,332 1/1968Reftmark 219/1055 3,422,240 1/1969 Parker .219/ 10.55

HIGH-FREQUENCY HEATING 3,643,055 r451 Fears, 19 72 3/l969 AndersonHaagensen ..2l9/ 10.55

Primary Examiner-J. V. Truhe Assistant Examiner -l-lugh D. .laegerAttorney-Stevens, Davis, Miller8z Mosher 1 1 ABSTRACT A high-frequencyheating apparatus, in which the highfrequency energy is' uniformlydistributed in a heating chamber for effectively heating the matter inthe heating chamber. An energy distribution modifying means is providedin conformity to the shape of the heating chamber and on at least oneof. coaxial inner and outer conductors defining a cylindrical passage,which communicates with a waveguide coupled to a higr-frequencyoscillator. The high-frequency energy from the high-frequency oscillatoris guided through the waveguide and the cylindrical passage to enter theheating chamber and is unifonnly distributed in the heating chamberthrough the energy distribution modifying means.

6 Claims, 10 Drawing Figures PAIENIEDFEB 15 I972 SHEET 2 BF 2 FIG.3

FIG.4

v tively heating the matter therein.

correcting means to obviate the nonuniformity of energy distribution inthe heating chamber.

The invention will nowbe described in connection with a preferredembodiment thereof with reference to the accompanying drawings, inwhich:

FIG. 1 is a perspective view, partly broken away, showing ahigh-frequency heating apparatus, with a top cover removed, embodyingthe invention;

FIG. 2 is a fragmentary sectional view, to an enlarged scale, showing indetail an inner and outer'conductor of a coaxial guide in the apparatusof FIG. I;

FIGS. 3 to show respective layouts of the heating chamber as well asrespective energy distribution correcting means conforming to the shapeof the heating chamber in the highfrequency heating apparatus accordingto the invention; and

FIGS. 6 to are fragmentary perspective views showing examples of theenergy distribution correcting means according to the invention.

Referring to FIGS. 1 and 2, a high-frequency heating apparatus accordingto the invention is shown having a heating chamber defined by top andbottom chamber walls 2 and 3, a front door 4 as well as by side and rearchamber walls (not indicated). The door 4 of the hearing chamber 1 ishinged by hinges 5 to a support base and carries a door handle 6 to openand close it. The heating chamber 1 is electromagnetically isolated fromthe outside when the door 4 is closed. Outside the heating chamber 1 isdisposed a' rectangular or boxlike waveguide 7 secured by means of bolts8 and nuts 9 to the top chamber wall 2 of the heating chamber 1. Thewaveguide 7 extends rearwardly ofthe heating chamber Land it is coupledto a high-frequency oscillator 10- disposed undemeath its rear portionand having a radiating antenna extending within the waveguide 7. Thewaveguide 7 communicates with a cylindrical passage fonned by a hollowcylindrical outer conductor 12 and a coaxial inner conductor 17. Theouter conductor 12 is disposed centrally on the top of the heatingchamber 1 and penetrates both the top wall of the heating chamber 1 andbottom wall of the waveguide 7. It is formed at its upper end with aflange 13, which is secured by means of welding to the waveguide 7, andat its lower end with lower extensions 14 radially spaced to correspondto the comers of the heating chamber 1, as is most clearly shown in FIG.2. The extensions 14 constitute an energy distribution correcting meansto provide unifonn energy distribution in the heating chamber 1. Theinner conductor 17 is secured to the lower end of a drive shaft 15 of aninsulating material such as polypropylene penetrating the top wall ofthe waveguide 7 and leading to a motor 16 suitably mounted on top of thewaveguide 7. The upper end of the inner conductor 17 is located withinthe waveguide 7, and the lower end thereof is located within the heatingchamber 1 and carries a rotary wing secured thereto by means of bolts 19and 19'. The rotary wing 20 has integral fins 22 and constitutes a fieldstirrer. A power source 21 for the high-frequency oscillator I0 isinstalled on the support base.

ductor I7, distributed thereby within the heating chamber I and absorbedby the matter being heated (not shown).

It will be appreciated that the rotary field stirrer wing 20 made ofametallic material according to the invention provides the function of akind of antenna, which may be obtained by appropriately adjusting thelength of the wing, and promotes the uniform distribution of the energyradiated from the wing in the heating chamber I as the wing is rotated.

Besides, the uniform energy distribution is further assisted by the fins22 integralwith the wing 20, which stir the energy 7 reflected from thechamber walls of the heating chamber I.

The rotary wing 20together with the integral fins 22 might provide trulyuniform energy distribution in the heating chamber if the heatingchamber-were cylindrical. For truly uniform energy distribution in theheating chamber of an otherthan circular layout, a sort of directivityconforming to the layout of the heating chamber is necessary. Theextensions 14 are provided for this purpose, andthey constitute anenergy distribution modifying means. They are radially spaced'inconformity to the layout of the heating chamber I.

FIGS. 3 to 5 show'examples of the arrangement of the energy distributionmodifying means 14 conforming to different layouts or shapes of theheating chamber 1. Other arrangements of the energy distributionmodifying means in conformity to other differentshapes of the heatingchamber are of tor or the innerconductor or to both the inner and outerconcourse possible.

The arrangement of the energy distribution modifying means shownin FIG.3 conforms to the square layout of the heating chamber. The arrangementin FIG. 4 conforms to a rectangular layout, and the arrangement in FIG.5 to a hexagonal layout. The configuration and dimensions of the energydistribution modifying means may also be determined in con- I vided,which are similarly located and spaced. In the embodiment of FIG. 8,notches 25 are formed, which are similarly located and spaced. In theembodiment of FIG. 9, portions 26 of an increased wall thickness areformed, which are similarly located and spaced. In the embodiment ofFIG. 10, apertures 27-are formed, which are similarly located andspaced. These energy distribution modifying means have the same effectof providing truly uniform energy distribution in the heating chamber. I

Other examples of the energy distribution modifying means in respect ofconfiguration and dimensions are also possible in' accordance with theinvention.

In accordance with the invention the energy distribution modifying meansmay be provided to either the outer conducductors, in place of providingto the outer conductor as in the foregoing embodiments.

Further, although the filed stirrer in the foregoing embodiment isprovided to the inner rotary conductor, the same effects may be obtainedby providing the field beater to an outer conductor, which is rotary,and which holds the inner conductor stationary.

1 What is claimed is:

I. A high-frequency apparatus comprising a high-frequency oscillator; aheating chamber for heating substances to be heated by thehigh-frequency energy produced from-said highfrequency oscillator; afirst waveguide for guiding the highfrequency energy from saidhigh-frequency oscillator to said heating chamber; a second waveguideconnected with said first waveguide, said second waveguide being acoaxial line consisting of a hollow cylindrical outer conductorprojecting into the heating chamber and an inner conductor extendingthrough and coaxial with said outer conductor; at least one stirrerattached to the inner conductor and rotated by a drive shaft provided inthe inner conductor; and a part for modifying the energy distribution inthe heating chamber uniformly formed on the outer conductor, said partcorresponding to the shape of the heating chamber. I

2. A high-frequency heating apparatus according to claim 1, wherein saiddistribution modifying part consists of protuberances'formed on theouter conductor, said protuberances corresponding to the respectivecomers or sidewalls of the heating chamber.

3. A high-frequency heating apparatus according to claim 1, wherein saidenergy distribution modifying part consists of metal pins provided onthe outer conductor, said metal pins corresponding to the respectivecomers or sidewalls of said heating chamber.

portions of an increased thickness formed on said outer conductor, saidincreased thickness portions corresponding to the comers or sidewalls ofsaid heating chamber. 6. A high-frequency heating apparatus according toclaim I,

. wherein said energy distribution modifying part consists of 4. Ahigh-frequency heating apparatus according to claim 1,

apertures formed in the outer conductor, said apertures corresponding tothe respective comers or sidewalls of said heating chamber.

' s a a: a:

1. A high-frequency apparatus comprising a high-frequency oscillator; aheating chamber for heating substances to be heated by thehigh-frequency energy produced from said high-frequency oscillator; afirst waveguide for guiding the high-frequency energy from saidhigh-frequency oscillator to said heating chamber; a second waveguideconnected with said first waveguide, said second waveguide being acoaxial line consisting of a hollow cylindrical outer conductorprojecting into the heating chamber and an inner conductor extendingthrough and coaxial with said outer conductor; at least one stirrerattached to the inner conductor and rotated by a drive shaft provided inthe inner conductor; and a part for modifying the energy distribution inthe heating chamber uniformly formed on the outer conductor, said partcorresponding to the shape of the heating chamber.
 2. A high-frequencyheating apparatus according to claim 1, wherein said distributionmodifying part consists of protuberances formed on the outer conductor,said protuberances corresponding to the respective corners or sidewallsof the heating chamber.
 3. A high-frequency heating apparatus accordingto claim 1, wherein said energy distribution modifying part consists ofmetal pins provided on the outer conductor, said metal pinscorresponding to the respective corners or sidewalls of said heatingchamber.
 4. A high-frequency heating apparatus according to claim 1,wherein said energy distribution modifying part consists of notchesformed in the outer conductor, said notches corresponding to therespective corners or sidewalls of said heating chamber.
 5. Ahigh-frequency heating apparatus according to claim 1, wherein saidenergy distribution modifying part consists of portions of an increasedthickness formed on said outer conductor, said increased thicknessportions corresponding to the corners or sidewalls of said heatingchamber.
 6. A high-frequency heating apparatus according to claim 1,wherein said energy distribution modifying part consists of aperturesformed in the outer conductor, said apertures corresponding to therespective corners or sidewalls of said heating chamber.